The HBT technique has been investigated mainly for the purpose of improving the high-speed performance of a bipolar transistor. In the HBT forming method investigated by the present inventors, high-temperature heat treatment (for example, at about 850 to 1200° C.) in a hydrogen gas (H2) atmosphere is carried out just before selective formation of an SiGe layer over a silicon (Si) substrate, for example, by the epitaxial method in order to remove a silicon oxide film mainly by a reduction reaction from the surface on which the SiGe layer is to be grown, thereby cleaning the surface.